1. Field of the Invention
The present invention relates to a recording/reproducing head, recording/reproducing apparatus, recording method, and reproducing method and, more particularly, to a recording/reproducing head, recording/reproducing apparatus, recording method, and reproducing method which record or reproduce data by injecting electrons.
2. Description of the Related Art
Along with the steady increase in the quantity of data in the recent information-oriented societies, a recording method capable of implementing a much higher recording density than usual and a recording apparatus based on it are desired.
A magnetic recording apparatus representing probe recording apparatuses has no wiring to access a recording layer that records data. Hence, there is no restriction on the complex device structure to prevent write errors in adjacent portions in the recording layer and any decrease in speed. In addition, no problem of heat arises because simultaneous access to many recording layers does not occur. Hence, the apparatus is advantageous in microfabrication.
Actually, the limit of the recording density of a recording medium is supposed to sufficiently exceed 1 Tbpsi (terabit per square inch). However, a recording head and reproducing head have a complex structure to control the direction of electron spin, and it is difficult to achieve microfabrication of 50 nm or less.
A probe recording apparatus that stores charges instead of magnetism has a simpler head structure than the magnetic recording apparatus, and therefore, microfabrication is possible. A scheme of heating a recording medium by a near-field optical head to extract electrons from the recording medium side (e.g., reference 1 (JP-A 2001-189030 (KOKAI))) and a scheme of heating a probe by light to extract electrons from the probe side (e.g., reference 2 (JP-A 2001-283479 (KOKAI))) are proposed actually. A data recording scheme of causing dielectric polarization by applying an external voltage to a ferroelectric provided in a recording medium (e.g., reference 3 (JP-A 2004-14016 (KOKAI))) is also proposed.
In references 1 and 2, however, the cost considerably increases, and the microfabrication limit of the near-field optical head is supposed to be about 20 nm or more. In reference 3, when the ferroelectric is microfabricated to 50 nm or less, ferroelectricity is lost.